Surface Of Ceramic Substrate Research Articles

The microstructure and properties of copper coating fabricated by high velocity arc spraying

In this paper, the conductive copper coating on the surface of silicon nitride ceramics was fabricated by high velocity arc spraying with copper wires. The results indicate that copper coating with porosity less than 2.4 % was obtained, and a metallurgical bonding between the copper coating and the ceramic substrate. The copper coating presented a high microhardness of 303HV which surpassed the copper alloy and the thin film deposited by electrodeposition. Moreover, the copper coating exhibited a superior conductivity of 27.5 MS/m. Due to the rougher surface of the copper coating compared to copper sheet, a jagged intermetallic compound (IMC) layer was promoted during soldering process. It is feasible that an excellent conductive copper coating on the surface of ceramic substrate can be fabricated by high velocity arc spraying.

Investigation of Silver Nanowire Transparent Heated Films Possessing the Application Scenarios for Electrothermal Ceramics

As transparent heated films (THFs) based on transparent conductive oxides (TCOs) are restricted by expensive raw materials and inappropriate fabricating film on curved surfaces because of its brittleness, silver nanowires transparent conductive film (AgWS-TCF) is an ideal alternative material for THF. However, there are still many problems to be solved in the electrical and thermal stability of AgNWs-TCF. In this paper, an Al-doped ZnO (AZO) nanoparticles produced by magnetron sputtering was used to modify and coat the AgNWs network, and the ceramic /AgNWs@AZO-TCF was obtained. Compared with ceramic/AgNWs-TCF, the sheet resistance of ceramic/AgNWs@AZO-TCF decreased from 53.2 to 19.3 Ω/sq, resistance non-uniformity decreased from 18.0% to 7.0%, and the inoxidizability, current-impact resistance, and failure voltage increased significantly. In addition, the electrothermal efficiency of ceramic/AgNWs@AZO-TCF is significantly improved after sputtering a SiO2 layer on the surface of ceramic substrate. Compared with ceramic/AgNWs@AZO-TCF, the temperature of ceramic-SiO2/AgNWs@AZO-TCF increases from 78.7 to 113.2 °C under applied voltage of 6 V, which possess the application scenarios for electrothermal-ceramics teacup (or tableware) to realize the function of heat preservation and disinfection.

Tunable resistance of MOFs films via an anion exchange strategy for advanced gas sensing

Because of their ultra-high surface area, large porosity and excellent structural tailorability, metal-organic frameworks (MOFs) are considered as outstanding candidates among sensing materials for hazardous gas detection. However, most of MOFs-based sensing films show weak film adhesion and low conductivity due to the poor formation ability of MOFs films by traditional sensor fabrication methods as well as the intrinsic insulating character of these MOFs. In this work, we propose a novel strategy to directly grow robust gas-sensing films based on pristine MOFs arrays (ZIF-67 nanosheets) in-situ on the surface of ceramic substrates. To improve the conductivity of MOFs arrays, anion-exchange method is applied to couple Prussian blue analogue (PBA) on the surface of ZIF-67 arrays. Structural characterization revealed that this permutation reaction can significantly improve the conductivity of the MOF films while their sheet-like structures can be mainly remained. Benefiting from the robust structure and improved conductivity, the as-designed ZIF-67/PBA films exhibited superior sensing performances such as good reproducibility, high response value (Rg/Ra=11.7), and fast response/recovery speed (5/182 s) towards triethylamine. This work provides a new strategy to fabricate MOFs gas sensors and paves a new way to modulate the conductivity of MOF films.

Pore engineering of Co3O4 nanowire arrays by MOF-assisted construction for enhanced acetone sensing performances

Array-based sensors have been regarded as excellent candidates for the gas-sensing elements owing to their low-cost preparation, great miniaturization potential as well as stable performance. However, it still remains a great challenge to prepare porous arrays and regulate their porosity to increase pores for gas transport and active sites for surface reactions. To solve this problem, the porosity of metal oxide arrays (Co3O4) that had grown directly in-situ on the surface of ceramic substrates was regulated by the constructing and oxidizing of MOFs (ZIF-67) that coated on the surface cobalt-containing precursor arrays. It was found that the porosity and surface area of Co3O4 nanowire arrays increased with the content of ZIF-67. The porous Co3O arrays with the highest porosity and surface area exhibited the highest response value (Rg/Ra = 16.7), the lowest optimal operating temperature (200 °C) as well as the fastest response/recovery time (4/39 s) towards acetone. These porous Co3O4 arrays are thus promising gas-sensing materials for acetone detection with excellent performances. This novel strategy to enhance the porosity of arrays can pave a new way to improve the gas-sensing properties of array film-based sensors.

Optimizing Electroless Plating of Ni–Mo–P Coatings Toward Functional Ceramics

Ni–Mo–P coatings are obtained at the surface of ceramic substrate by electroless deposition using palladium as a surface catalyst. The influence of catalyst activation conditions on coatings’ properties was assessed by structural, morphological, electrical, mechanical measurements and adhesion strength by using X-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, Hall effect and nanoindentation techniques, respectively. The results indicated the formation of dense, continuous and uniform coatings consisting mainly of Ni. The coatings obtained at 300 °C for 12 h exhibited the best electrical properties, namely resistivity of 9.32 μΩ cm, smaller roughness (Ra 0.090 µm) and average mechanical properties. The adhesion tests showed a firm adherence of the Ni–Mo–P coatings to the ceramic surface. The results of this study could offer an approach for obtaining conducting ceramic substrates in order to be employed in photovoltaic applications. The performance of demonstrative heterojunction solar cell obtained with such metallized ceramic is indicative of the high potential of the Ni–Mo–P electroless coatings for functional ceramics.

Etching by a beam of fast argon atoms of gas dynamic grooves on the surface of ceramic substrates

A method of manufacturing the grooves of the end seals from high-strength dielectric materials is proposed. Uneven depth (no more than 10%) imposes a limit on the processing time. Grooves with a depth of ∼5 μm in corundum substrates can be made using a source of fast argon atoms in ∼1 hour with their energy of 3 keV and equivalent beam current of 1 A.

Aerosol Jet Printing of Platinum Microheaters for the Application in Gas Sensors

This paper presents the results of characterization of microheaters fabricated on the surface of ceramic substrates by aerosol jet printing with commercially available platinum ink containing colloidal particles with the average size of about 100 nm. The microheater under study represents planar microstructure with variable cross-sectional area comprising narrow segment capable of being heated up to few hundred degrees when current is passed through. The narrow segment is fabricated in the form of single line with the width and height of 50 μm and 6.7 μm, respectively. To remove the organic substance from the deposited material (dry residue of the ink), the printed microheaters were fired at 150°C for 20 min. The dependence of the operating temperature on the power consumed by the microheater was obtained from the measurements of direct current resistance as a function of consumed power with the use of previously determined temperature coefficient of the material (3.910−3 K−1).

Improved functional performances of traditional artistic pottery by sol-gel nanoparticles deposition

This work is focused on the realization of a new manufacturing process based on the introduction of TiO2 nanostructured coatings on the surface of red earthenware pottery for domestic use. The aim of the study is to improve the technical properties of the product made from lime and iron-rich clays used to produce traditional artistic Tuscan pottery (Italy). The identified strategy involves the application of nanoparticles onto the surface of ceramic substrates via a sol-gel based process; the initial porosity of the Earthenware promotes the insertion of inert nanoparticles in the outermost part of the ceramic material by simple immersion of bisqueware in the colloidal solutions of nanoparticles. Morphological investigation of the functionalized surfaces has been carried out by scanning electron microscope and atomic force microscopy, while the effectiveness of the treatment was checked by evaluating the water absorption capacity in compliance with the standard method AS-1012.21-1999. The obtained results show a reduction of surface porosity, which turns into a reduced water uptake respect to the traditional pottery, maintaining, at the same time, identical aesthetical characteristics.

Comparative Evaluation of the Performance of Commercial Inks Used in Digital Decoration of Ceramic Tiles

The decoration technique of inkjet digital printing, because of its numerous advantages, has revolutionized the ceramic tile industry in recent years. Because of the peculiarities of this technique, there is no methodology to thoroughly evaluate the performance of commercial inks, in order to assist the industry in the selection of the inks. Thus, ceramic tile producers cannot predict the ink yield, the image definition, or the color gamut provided by the inks and inks from different manufacturers may differ significantly in these aspects. This work proposes a methodology for comparative evaluation of the performance of industrial inks for digital printing, based on the colorimetric evaluation of the dots produced by the inks and their spreading behavior on the surface of ceramic substrates. The results revealed important differences in the performance of commercial inks, confirming the need of a methodology to evaluate the inks.

High performance room temperature NO2 sensors based on reduced graphene oxide-multiwalled carbon nanotubes-tin oxide nanoparticles hybrids

A facile and effective strategy has been successfully developed to synthesize reduced graphene oxide-multiwalled carbon nanotubes-tin oxide nanoparticles (rGO-CNT-SnO2) hybrids by hydrothermal method. The combined characterizations of X-ray diffraction, Raman spectrum and Transmission electron microscopy were used to characterize the samples thus obtained, indicating the successful preparation of rGO-CNT-SnO2 hybrids. A room temperature NO2 sensor was fabricated by dropping the dispersion of rGO-CNT-SnO2 hybrids on the surface of ceramic substrate previously printed Au electrodes. Most importantly, the sensor based on rGO-CNT-SnO2 hybrids shows high response, fast response and recovery rate, high selectivity and good stability, which are much better than NO2 sensors based on pure rGO and rGO-SnO2 hybrids.

Nanoparticle-decorated ceramic as substrate in surface enhanced Raman spectroscopy

Laser-assisted method for fabrication of nanoparticles on the surface of ceramic substrate is presented. The method is based on laser dewetting of thin metal film deposited on the substrate. Using this technique, gold nanoparticles on alumina ceramic surface are fabricated. It is shown that the processing parameters can influence the properties of the fabricated structure, as at certain conditions a homogeneous cover of nanoparticles with narrow size distribution can be achieved. The processed surfaces are tested as substrates in surface enhanced Raman spectroscopy of a standard dye. The efficiency of the substrates is estimated by the ability of detection of the dye at nM concentration and it is compared to that of thin gold film on ceramic substrate. The strongest enhancement is observed for the sample where Au film is not completely decomposed and the structure consists of thin film and nanoparticles aggregates. The proposed method has potential application in fabrication of cheap and reliable substrates for Raman spectroscopy analysis with high sensitivity and also in catalysis.

Super Smooth Modification of Al2O3 Ceramic Substrate by High Temperature Glaze of CaO–Al2O3–SiO2 System

The rough surface of ceramic substrate is an obstacle for the scale down of line-width for thin film passive integrated devices (PID). In this paper, a modification method for Al2O3 ceramic substrate with super smooth in surface was proposed. Coating a layer of CaO–Al2O3–SiO2 (CAS) glass was performed to flat the rough surface of alumina substrate by sol–gel method. It was found that addition of 0.06% V2O5 can inhibit the recrystallization of the glaze. The root-mean-square (RMS) roughness of the glazed substrates reached a surprising flatness as small as 0.5 nm, and its melting temperature is higher than 1300 °C. This substrate with super flatness and high temperature endurance may be promising for high performance thin film devices.

A model of substrate surface roughness effect on the electrical properties of thin films

In situ resistance and thickness measurements during deposition of thin NiCr films onto various substrates revealed an effect of the substrate on the electrical transport parameters. On the rough surface of ceramic substrates the thickness dependence of the resistivity could be well fitted to the simple Fuchs-Sondheimer size effect model, however, both the resistivity δ o and the mean free pathλ 0 was higher than in the case of smooth glass substrates. It is shown that these deviations-appearing as a pseudo size-effect are mainly caused by the differences in the surface geometry of the substrates. Nevertheless, the material and crystal structure of the substrate have also an influence on the growth mechanism and, consequently, on the structure and electrical properties of the films. A simple model of this virtual size effect of the electrical resistivity in thin films caused by the surface roughness of the substrate is presented.